The goal is to use this new membrane for solid-polymer fuel cells that can serve as power sources in cars and in portable information terminals.

In a solid-polymer fuel cell, the polymer membrane separates the two electrodes while allowing hydrogen ions to pass from one side to the other.

The conventional material used for this membrane must be kept under humidity conditions of higher than 90 per cent. Because this high humidity is difficult to maintain, solid-polymer fuel cells have a problem with stable output.

The new polymer membrane solves this problem. It is based on a fluorine-type polymer which is irradiated to bind more sulfonic acid, a molecule that facilitates the transfer of hydrogen ions across the membrane.

In tests under temperature and humidity conditions of 80 C and 70 per cent, the new polymer membrane exhibited an ion transfer rate some four times as high as a conventional membrane.